CVE-2026-80546 (GCVE-0-2026-80546)

Vulnerability from cvelistv5 – Published: 2026-08-26 14:37 – Updated: 2026-08-27 05:01
VLAI
Title
s390/zcrypt: Improve CCA CPRB length and overflow checks
Summary
In the Linux kernel, the following vulnerability has been resolved: s390/zcrypt: Improve CCA CPRB length and overflow checks The xcrb_msg_to_type6cprb_msgx() function lacks proper input validation, creating security vulnerabilities: 1. Integer overflow after CEIL4 alignment: Signed int variables could overflow during 4-byte boundary alignment, causing undersized buffer allocations or incorrect bounds checking. 2. Missing minimum size validation: The CPRBX structure is copied from userspace without verifying sufficient buffer length. Undersized buffers cause uninitialized memory access when reading structure fields like cprbx.cprb_len and cprbx.domain. 3. Arithmetic overflow in sum calculations: Adding control block and data block sizes could overflow, bypassing size checks and enabling buffer overflows. Fix by using size_t for length calculations, adding U32_MAX boundary checks after alignment, validating minimum control block size before copying from userspace, and detecting sum calculation overflows.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: e2c6d91eb8b1533753755f07803e47eceed263d0 , < 50fe5133dcb46449daf2435fa705264364411129 (git)
Affected: e2c6d91eb8b1533753755f07803e47eceed263d0 , < 35ac6754ba6da45fd193f5ce3f665f7490b830d5 (git)
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Linux Linux Affected: 7.1
Unaffected: 0 , < 7.1 (semver)
Unaffected: 7.1.10 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/s390/crypto/zcrypt_msgtype6.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/zcrypt: Improve CCA CPRB length and overflow checks\n\nThe xcrb_msg_to_type6cprb_msgx() function lacks proper input\nvalidation, creating security vulnerabilities:\n1. Integer overflow after CEIL4 alignment: Signed int variables could\n   overflow during 4-byte boundary alignment, causing undersized\n   buffer allocations or incorrect bounds checking.\n2. Missing minimum size validation: The CPRBX structure is copied from\n   userspace without verifying sufficient buffer length. Undersized\n   buffers cause uninitialized memory access when reading structure\n   fields like cprbx.cprb_len and cprbx.domain.\n3. Arithmetic overflow in sum calculations: Adding control block and\n   data block sizes could overflow, bypassing size checks and enabling\n   buffer overflows.\n\nFix by using size_t for length calculations, adding U32_MAX boundary\nchecks after alignment, validating minimum control block size before\ncopying from userspace, and detecting sum calculation overflows."
        }
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            "baseSeverity": "HIGH",
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            "version": "3.1"
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              "lang": "en",
              "value": "AV:L - The bug is in xcrb_msg_to_type6cprb_msgx(), reached only from the ZSECSENDCPRB ioctl on the s390 zcrypt character device (zcrypt_unlocked_ioctl -\u003e zsecsendcprb_ioctl -\u003e _zcrypt_send_cprb -\u003e prep_cca_ap_msg); there is no network, adjacent-radio, or physical-bus entry point.\nAC:L - An attacker with a zcrypt fd fully controls the ica_xcRB length fields and CPRB buffers and can craft values that bypass flawed CEIL4/sum checks on every ioctl; no race, timing dependency, or uncontrolled memory layout is required.\nPR:L - Exploitation needs only local access to a zcrypt device node with ZSECSENDCPRB permitted via zcrypt_check_ioctl(); on IBM Z/LinuxONE admins routinely delegate such access to non-root crypto service accounts through custom zcdn nodes, not init-namespace root alone.\nUI:N - The attacker triggers the flaw directly by issuing ZSECSENDCPRB with a crafted ica_xcRB from their own process; no separate victim action such as mounting a filesystem or opening a file is required.\nS:U - Impact is heap corruption and kernel memory disclosure within the host kernel address space during AP message preparation; it does not cross a VM, IOMMU, or other changed security-authority boundary.\nC:H - Undersized request_control_blk_length copies fewer than sizeof(CPRBX) bytes yet the code reads cprbx.cprb_len and cprbx.domain from uninitialized kmalloc memory; integer-overflow bypasses can also yield out-of-bounds reads beyond the allocated ap_msg buffer.\nI:H - Signed-int CEIL4 alignment and sum overflows can make ap_msg-\u003elen smaller than copied data and place req_data before the kmalloc buffer, enabling z_copy_from_user() heap buffer overflows and attacker-influenced memory corruption suitable for control-flow hijack.\nA:H - Heap underflow/overflow and corrupted AP message buffers can immediately oops or panic the kernel; prep_cca_ap_msg runs before any crypto hardware is required, so the crash primitive is repeatable from ioctl alone."
            }
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      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-27T05:01:33.755Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/50fe5133dcb46449daf2435fa705264364411129"
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          "url": "https://git.kernel.org/stable/c/35ac6754ba6da45fd193f5ce3f665f7490b830d5"
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      "title": "s390/zcrypt: Improve CCA CPRB length and overflow checks",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80546",
    "datePublished": "2026-08-26T14:37:17.550Z",
    "dateReserved": "2026-08-26T14:34:25.765Z",
    "dateUpdated": "2026-08-27T05:01:33.755Z",
    "state": "PUBLISHED"
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-27T07:04:16+00:00",
      "cve": "CVE-2026-80546",
      "id": "CVE-2026-80546",
      "initial_release_date": "2026-08-26T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: s390/zcrypt: Improve CCA CPRB length and overflow checks",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80546.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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